IRDA doesn't flicker in the visible spectrum, and thus fails to cause hilarious non-fatal seizures in coworkers, which, I'm assuming, is the whole point of this new technology.

The real problem there is (particularly bicycle) lighting systems which intentionally pulse at ~10 Hz. A lighting system which transmits data by inserting fast negative going pulses into LEDs is unlikely to cause problems.

Background: I ride a bike and I have epilepsy, but my EEG results suggest my condition is not photosensitive.

I mean seriously, I think we all know that if this thing operates at 4Mbps, it can't be pulsing at anywhere near the brain-fritzing frequency. But that isn't the point. The point is, you epileptics are funny because of how you flop around.:P

I think we all know that if this thing operates at 4Mbps, it can't be pulsing at anywhere near the brain-fritzing frequency.

Consider that activity LEDs on older hubs were connected directly to the data lines and could be used to transmit data. These LEDs also pulsed visibly. These LEDs could certainly pulse at visible rates because the data starts and stops at those rates. Even if "down" is "on" a second or so of sustained load would make the lights dim. Obviously the drivers would work to avoid that.

Sorry about wrecking your joke. I just think that LEDs are both tempting and dangerous to pulse at certain rates. Lots of trucks a

IRDA doesn't flicker in the visible spectrum, and thus fails to cause hilarious non-fatal seizures in coworkers, which, I'm assuming, is the whole point of this new technology.

Joking yes. But being a self-proclaimed expert who hasn't even read the article my guess is that they are piggy-backing on the PWM commonly used to control LED brightness. The PWM frequencies for normal LED control are in the kilohertz range which is 100s of times faster than is visible to the human eye.

Most rooms have more than one lightbulb. If they are all using PWM to control brightness it could be hard to pick out the data from just one. Also you need some kind of receiver in the bulb for two way communications as well.

Infra red makes more sense. A single high power IR LED can cover an entire room. As it happens I have recently been experimenting with a system that uses a single IR LED to broadcast the current time so that all the clocks in my room can receive an accurate setting. I was planning to us

A wired connection requires a physical cable to be run to a specific location through the floor or ceiling and if the decision is made to rearrange the cubicles it adds thousands of dollars in rewiring. WiFi eliminates this requirement but necessitates an extra FCC license for every connection driving up the cost of the equipment. I suspect this would initially bypass the FCC as it does not use the RF spectrum. That's not to say at some point the feds won't decide they own the flickering light spectrum as w

It would be interesting to know exactly how much of a device's purchase price is caused by FCC anti-interference interference(sorry, couldn't resist); though there probably isn't a single number, depending on how many devices were manufactured with one model certification, and how much shielding/redesign/clocking cleverness was required to comply; but I'd be surprised if it were high enough to drive adoption of this optical stuff, unless they have the LOS issue truly figured out and are willing to accept ve

A wired connection requires a physical cable to be run to a specific location through the floor or ceiling and if the decision is made to rearrange the cubicles it adds thousands of dollars in rewiring. WiFi eliminates this requirement but necessitates an extra FCC license for every connection driving up the cost of the equipment. I suspect this would initially bypass the FCC as it does not use the RF spectrum.

Don't forget to paint over the windows or your competitors only need to rent a room across the road to get all your datas...

The big problem with these things is they need to be lighting the room for the data to flow... when everyone goes home and someone turns out the lights it cuts off all the PCs in the room and you can't do remote admin stuff like software updates and security patches. The solution of leaving the lights on will get the environment crazies on your back.

The biggest problem with these patents, is everything they are claiming has been done before so all they are claiming is, they are doing with leds. So blindingly obvious that all previous technology applications facilitated by light emitting devices will transfer over to LEDs. So if they invented LED's fine if they did not, gees, just fuck off.

Hint, hint, a video display device communicates information to the human brain via lcds and leds, making use of the biological receiving devices of the human eye,

There's the issue of WiFi having quite complex propergation patterns. Whereas with visible light to can easily tell where the coverage area and confine it to specific rooms without needing exotic building materials.

Not really... visible light can be as unpredictable... light reflects off walls and floors and can propagate quite far... you can be upstairs in bed and notice the downstairs light is still on since there is a faint light visible around the edges of the closed bedroom door...

WiFi doesn't have or require F.C.C. licensing for the end users. It does have to comply with some F.C.C. rules, but any digital circuit switching at r.f. speeds does too even if not designed to radiate r.f.

There are F.C.C. rules that apply to all electronics using radio frequency energy. The goal is to limit r.f. radiation that may cause interference. Anything that has circuits switching at an r.f. rate, even power supplies, is covered by the rules. The associated testing

I don't see how this is much better than the IRDA infrared that used to be built into laptops, printers, mice, etc. It got replaced by radio technology several generations ago.

There were, very briefly, vaguely wifi-esque IR "access points" designed for using IRDA connections in entire rooms(as opposed to the usual point-to-point between adjacent devices case). Some even supported multiple devices. I think the amount of IR you needed to pump out to get a reliable link without forcing the user to manually handle line-of-sight pretty much killed that one, though. I think these "access points" and contentional device-device IRDA were supposed to coexist in much the way wifi and bluet

Yeah, my old-school iPAQ's 900MaH battery would probably not be happy about running a Luxeon for long...

On the other hand, with the absolutely spooky optical MEMS stuff and CMOS/CCD imagers you can get for absolute peanuts today, you might be able to whip up a little solid-state device that tracked 2 or 4 "target" LEDs located around the room's receiver and then steered a low power IR laser right into its lens...

That would still only work with a clear LOS, and with the emitter window less than 90 degr

this is better than current IRDA used by laptops because that one is slow and a pain in the rear to use. Also, light is less vulnerable to interference / interception than wifi

From what i see in the summary description from the article they are using a modified RONJA design but instead of the long-range with narrow beam they adapted it for a wide angle with a way smaller distance, fit for office ceiling usage.

A RONJA optical network has been capable of working at 10 mbps full duplex at 1,4 KILOMETERS (about

P.S.
about the patent thing... this smells to me like patent system abuse... ronja was already using LEDs for network communications in 1998, using an AUI interface.the only addition these guys made is mounting a ronja system into a light frame and using spectrum filters to filter out normal light

The patent, aside from using "degrees Kelvin" twice, only covers combining the communications device with building illumination. This is a remarkably pointless thing to do and conveys no obvious benefit. (Oddly, the patent also would only be infringed by a system including at least one name tag that communicates with the system.)

Kohls has had technology like this in their stores for a little while now. They use the lights to update little LED price tags throughout the store. I think Fujitsu makes the tech, though I could be wrong. Anyone wanna help me out on this?

When I worked at JcPenney we would waste a day just ticketing items..... and oftentimes did not finish because of customers demanding service. Having signs that automatically update is the quick and labor-saving solution. Also helps to avoid fines when the government audits the store and finds "Sale $9.99" for a promotion that ended three days ago.

State governments routinely audit stores to verify the price charged at the register matches the price advertised on the sign. When I was at JCP the corporation had been caught twice - once by Pennsylvania in the early 90s and again by Texas in 2002.

Whether they have been caught or not (and twice in 20 years is approaching zero errors with the millions of price tags they put out in that time) is irrelevant to the question of whether state governments "routinely audit stores" without any complaints. My understanding is that they do not, and you've said nothing that contradicts that opinion.

Well then I guess JCPenney had a corporate, continent-wide meeting for their ~100,000 employees to emphasize the importance of proper pricing for no reason at all??? I think you're wrong.

Feel free to feel I'm wrong, but nothing there indicates that the problems found were the result of random audits. My opinion is that there were errors noticed by patrons that were then reported for a very targeted investigation, not the result of some government agency that routinely audits stores without complaints.

Kohls has had technology like this in their stores for a little while now.

A little while? My local food store had that in the early 90s. Had some weird modulator thing that plugged into the florescent lights. It was some kind of weird boost/buck converter that varied the line power / light brightness by a volt or so from cycle to cycle. I had the EE background to understand it but no one at the store knew how it worked.

The interesting thing is if you only have a couple tens of thousands of price tags, it doesn't take a very high bandwidth signal to reprice everything in a cou

The "integrated security" of the "illumination apparatus" means you can kill the communication link by quickly putting the computer with the "special modem" under your desk, and out of line-of-sight with the ceiling LEDs.

With enough power, you could certainly saturate whatever receiver tech they are using(presumably some sort of reasonably high speed photosensitive semiconductor, TFA isn't clear on what kind); but in the visible spectrum that sort of thing would be pretty noticeable. If they are actually just including some IR LEDs in their lamp array(which isn't entirely unlikely, "white" LEDs, since they are phosphor-coated blues or UVs, actually have lousy switching speeds because the phosphor keeps glowing momentarily after the diode is turned off. Though they could, I suppose, be using RGB arrays, which would have full switching speed...) "flood" interference would be less obvious; but still pretty unsubtle.

Because of little things like "eye safety" and "that guy in the truck with the generator and 5kw of stage lighting is pretty obvious at 300 meters" the classic "directional antenna and illegal power levels" that works so well on Wi-Fi probably won't work on this thing. On the other hand, TFA makes the company sound like they decided to go it alone, develop all their own patented tech and protocols and stuff. If the history of RF is anything to go on(Why hello WEP and the assorted nameless 900mhz and 2.4ghz cordless phone systems, we were just talking about you...) people who do that tend to make protocol and/or cryptographic mistakes. Assuming this stuff ever gets out of complete obscurity, I assume that snarky grey-hats will be flooding the system with garbage frames at defcon and you'll be able to buy little LED flashlights from ebay that exploit buffer overflows and execute arbitrary code on the microcontrollers in the ceiling fixtures...

I would say that it depends. It may work just fine with reflected light so it may not be an issue.It is an interesting idea for things like automation and data acquisition as well as location services.imagine this in a large corporate campus. If you need to find someone or something each room would have an identifier telling you where you are.A lamp could tell you that it is on or off, an AC unit could be reset. It will really depend on how cheap it all is.

If it operates in the infrared spectrum, the bonus is that most glass blocks it, so it would be harder to get a signal. The downside is, a sufficiently sensitive thermal camera with LoS to the bulb or a reflector in LoS with the bulb would give it to you.

If it operates in the infrared spectrum, the bonus is that most glass blocks it, so it would be harder to get a signal. The downside is, a sufficiently sensitive thermal camera with LoS to the bulb or a reflector in LoS with the bulb would give it to you.

Infrared devices of the kind that you're describing don't operate in the thermal part of the spectrum. They use near-infrared light, which is easily visible through most kinds of glass.

Actually glass is transparent to Infrared, which is why camera sensors have a sheet of glass over them which has a very expensive coating on the surface that blocks near and mid IR frequencies. I think you might be thinking of the UV spectrum which passes far less easily through standard glass.

Modern window glass is typically formulated/coated to absorb or reflect UV and infrared as much as possible while transmitting as much visible light as desired. Not sure if it would be enough to block a signal at a particular infrared wavelength or not.

When the power company comes by your house to do a thermal image, the windows always show heat loss/gain (depending on outside temperature). Glass does not block infrared. It does block UV, which is why reptile keepers can't put their UV lights on a glass aquarium top (but can for their infrared heaters).

Ok here's an easy test to confirm. Get the TV remote, your phone and an assistant. Have the assistance stand outside and point the TV remote inside through the window and press buttons. In the meantime set your phone to take a picture (cameraphones are far better at this than most digital cameras), and just look at the remote through the eyes of the cameraphone. You should see the LED pointed at you light up quite well. This is near-IR passing through.

Although I know that you're being sarcastic and a troll... I must point out that unless your laser is operating in a complete vaccum, there is some diffraction of the beam thanks to particles of dust and what-not in the air.

They're also working on a getting a patent for a new modem where you just set the phone headset right on the modem, by sticking both round parts in little earmuff thingies. Apparently it's only good for a couple hundred bits per second now, but they claim the next version will reach speeds in excess of 1000 bits per second. No word on whether it will work with cell phones.

From what I've read about this, while the LED lights are optical, the transmission line, aka the power line will still be used to carry data transmissions to and from the LED lights, I don't see how this or any other BPL tech being allowed by the FCC then again anything these days is allowed to pass through and transmit whatever it wants all over the Shortwave radio bands under FCC Part 15 rules, Plasma TV's being just one example which plasters the lower shortwave radio band with an insane amount of interf

I think that's what the patents are for. They don't use BPL. The light fixtures are located in dropped ceilings. Above the ceiling each light fixture has another light sensor. The data comes from yet another lightbulb even higher above the dropped ceiling. Those really high up lightbulbs use WiFi.

I think that's what the patents are for. They don't use BPL. The light fixtures are located in dropped ceilings. Above the ceiling each light fixture has another light sensor. The data comes from yet another lightbulb even higher above the dropped ceiling. Those really high up lightbulbs use WiFi.

[0088]The lights shown in FIG. 5, in accordance with an embodiment of the invention, will have AC wiring with data carriers such as S-BPL, and static locations encoded into the system. Thus a person 190 entering a hallway 192 with a communications badge 170 could use only those lights needed for his travel. As the person progresses toward a destination, the lights behind may be no longer needed and so may be programmed to turn off.

Power, which may be either AC or DC current is coupled through a power line bridge 150 with data from a network cable input, for example. The source of the data is not critical to the operation of the present invention, but may include various computer outputs such as might, for exemplary purposes, include control processor output or network connections such as commonly found on Local Area Networks (LAN), Wide Area Networks (WAN) or through the Internet. In accord with one embodiment, the wiring between power line bridge 150 and LED light source 161 is shielded by passing through a conduit or the like, defining a Shielded Broadband-over-Power-Line (S-BPL) connection that is both resistant to interfering communications and also produces almost no radiant energy.

And:

[0085]As seen in FIG. 4, the electrical wiring in the hallways and/or rooms may include BOPL.

At least they are considering using shielded power cabling, aka "S-BPL", but I would think using WiFi would be a wiser choice, one lousy installation of S-BPL c

From what I've read about this, while the LED lights are optical, the transmission line, aka the power line will still be used to carry data transmissions to and from the LED lights, I don't see how this or any other BPL tech being allowed by the FCC

How is that not a problem for (say) cat 5 cable? Maybe because it consists of twisted pairs? So twist the power cable, or shield it, or plug your cat 5 directly into the light fitting as the data input.

You can't twist power cable, bad things happen, like current appearing on the neutral line from the live line, and things like reflected power heating up the cable, instead of transmitting power the cable will then just act as a heater, and a large amount of current making it back to the transformer, burning that out and tripping fuses, among other things.
Hence why you get a warning sticker on every appliance with a really long extension cord on it, please don't lay the power cable in a circular fashion.

At least this is true in a single phase system, 3 phase systems can be twisted to a certian limited extent, its called Transposition. and is done to balance out the voltage and current of each phase with one another.
Dunno what effect it would have on a single phase transmission system.

I was thinking more about modulating the DC feed to the LEDs but as you point out the data and power circuits are going to have to come together at some point and I suppose the solutions to that problem are isolation and grounding. Once standards are developed for both it should go okay. Its possible to do it safely, even if the switches have to be on a fibre backbone, or some such.

I was thinking more about modulating the DC feed to the LEDs but as you point out the data and power circuits are going to have to come together at some point and I suppose the solutions to that problem are isolation and grounding. Once standards are developed for both it should go okay. Its possible to do it safely, even if the switches have to be on a fibre backbone, or some such.

I suppose you could have a CAT5 switch in every section of a building which feeds data to every light socket via means of CAT5, but uses a fiber backbone for the long haul back to a central point, that would prevent lightning from passing any further past that room or section of a building.
But I would imagine maintenance after a lightning strike or power surge would then require the complete disassembly of the entire roof to remove all of the dead and melted CAT5 and power cabling, not too different to wh

What I would like to see is a combination of this technology along with laser technology to distribute throughout an entire room invisible laser light, along with a fiber optic cabling that is tacked onto the side of power line cabling, its a sensible combination of power distribution and data distribution all rolled into one single power cable, so every light socket then automatically becomes a high bandwidth laser reception and transmission point, and every portable device then transmits back to the light

The reason shortwave as you call it is useful in emergencies is because ham operators can just cobble radio transmitters and receivers together out of parts lying around. They need is to form a tuned circuit and then start keying out morse and a crystal radio receiver to receive it. They understand about propagation and interference and just why human to human morse solves such problems in a worse case scenario. And it won't take too long for a ham operator to build an AM or even an SSB transceiver.

The first generation of the LVX system will transmit data at speeds of about three megabits per second, roughly as fast as a residential DSL line.

Is that physical layer rate? If so, what's the rate after protocol overhead?

Let's assume that is the physical layer rate. Which would make it three and a half times slower than 802.11b, and 18 times slower than 802.11g, which is virtually everywhere. And, drumroll please, at least one hundred times slower than 802.11n, which is 300-600Mbit/sec (physical layer speed.)

The trouble with 3Mbit/s is that, while it is luxury by the standards of "ambient" devices(ie. anything that you would consider using X10, GSM/SMS, zigbee, assorted proprietary facilities automation stuff, etc. for) it is painfully low unless the ratio of computers to light fixtures approaches 1(and, not just light fixtures; but optically separated light fixtures that don't interfere with one another; if this is anything like RF wireless, that physical layer rate has to be shared between all devices in the

Hide a sensor anywhere nearby, and you can read all the internal traffic.Drop a tiny node in a plushy on someones desk, spewing out all sorts of Window virus, and see how long it takes for the IP staff to find it.Shine a modulated laser beam through a window, and disrupt all the network traffic in an office.

Light therapy [wikipedia.org] for Seasonal Affective Disorder [wikipedia.org] ("SAD") can be implemented with LEDs. While it's typically used in 30min bursts first thing in the morning, I wonder if it can be spread out through a longer time and worked into standard lighting via this kind of array. Very intersting...

It's used to send pricing information to LCD price displays attached to shelves via the supermarket lighting (it's done at night when there's no-one around to be affected by it, and in any case since it's at a much higher frequency than the usual 50Hz flicker it wouldn't be noticed anyway). Think of the usual paper price tags in plastic holders attached to shelves, but now they have LCD displays and are updated automatically by modulating the in-store lighting.

Mohsen Kavehrad, a Penn State electrical engineering professor who has been working with optical network technology for about 10 years, said the approach could be a vital complement to the existing wireless system.
He said the radio spectrum usually used for short-range transmissions, such as Wi-Fi, is getting increasingly crowded, which can lead to slower connections.
"Light can be the way out of this mess," said Kavehrad, who is not involved in the LVX project.

It saves the company from running cable that last average of 100 feet or so from the wiring closet to each desk, multiplied by the number of desks on the floor (in this building there are about 100 desks per floor) multiplied by the number of times cube moves take place (you don't want to know how often this is, but triennial is not far from the truth) multiplied by the cost for an electrician to run a single line of cable. I think the average cost to pull a single run ranges from about $200-$400 on up, de

Thanks. My back-of-the-envelope is a lot less optimistic than yours, as I was trotting out worst cases on all counts.

What I really wanted to do was answer the GP as to "why" a company might want to avoid the last-mile expenses of a cubicle farm. I don't think for a moment that it's a good idea, mind you, because I agree that hard-wired installations are always technically superior to wireless in terms of performance.

Ouch. That's rough. You would almost be better off with something like shitty HughesNet with their 250Mb per day bandwidth cap. Of course latency would be an issue. Also, who's the asshat that modded C64 offtopic? I suppose the bit about comcast doesn't add anything useful to the discussion, but it is at least partially related to the article at hand. If anything my comment is offtopic.

Parent was making a joke, probably, but back when 10Mbit network hubs were the latest thing the LEDs would flicker directly with activity and it actually was possible to spy on the network given determination and the proper equipment.

You know, I heard rumors about that, but I don't see how it could have possibly worked. The light flickered as traffic went by. Knowing that a packet was sent is useless if you don't know the payload of it.

This is a different case entirely though. Well, mostly. They've reinvented fiber optic networks, without the fiber. Of course, that increases the noise for the receiving end, the chances for interception, and the ability for someone to break a connection with a Post-It n

Either they licensed them, or they lapsed; but optical wireless remained relatively uncommon, outside of IRDA(and, of course, almost every remote control ever made, except for the earliest acoustic models and a few fancy BT or wifi networked ones).

For whatever reason, there was one area where absolutely enormous numbers of IR wireless keyboards showed up: Hotel TV entertainment systems(I think "lodgenet" may have been one, my memory is a little fuzzy). For various usurious fees, you could use the keyboar